[PATCH] D141464: [X86]: Match (xor TSize - 1, ctlz) to `bsr` instead of `lzcnt` + `xor`

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a comment.

We have TuningFastLZCNT which should be a good enough predicate to control when NOT to perform this fold - you will need to add test coverage to clz.ll for fast/slow lzcnt


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D141464/new/

https://reviews.llvm.org/D141464